U.S. Pat. No. 3,789,638, Roberts, Cohn and Ward, "Rotary Disc Tumbler Lock Construction", dated Feb. 5, 1974, teaches the art of construction of an improved mechanical, key operated lock with a high degree of resistance to surreptitious entry methods and which is simple and economical to construct. This patent also teaches one method of key construction for the operation of such a lock.
U.S. Pat. No. 3,668,909, Roberts, "Settable Key and Coding Mechanism Therefor", dated June 13, 1972, teaches the art of construction of an improved mechanically settable key for use in conjunction with a lock construction as taught in U.S. Pat. 3,789,638 referred to above.
U.S. Pat. No. 3,905,213, Roberts, "Removable Core Differential Mechanism", dated Sept. 16, 1975, teaches the art of construction of an improved removable core capability and a key adaptation for operating same which is applicable to a lock construction as taught in U.S. Pat. No. 3,789,638 referred to above.
The key constructions and warded tumbler as taught in this application is a continuation of the inventive effort to teach new art as it is discovered on improvements, simplifications and greater adaptability of key constructions related to the above referenced U.S. Patents.